Barrier laminates for containment of essential oils, flavors, oxygen and vitamins and cartons made therefrom

ABSTRACT

A laminate providing an effective barrier to the migration of essential oils and/or flavorings, such as d-limonene and for the retention of Vitamin C, is provided comprising from the outer surface to the inner surface, a paperboard substrate, a web of nylon directly coated thereon, a web of Surlyn overlying and in contact with said nylon web and a web of olefin overlying and in contact with said Surlyn web. Preferably the paperboard substrate is also coated on the external surface thereof with a web of heat sealable polymer. Containers constructed from such laminates are especially useful as fruit juice containers which enable significant flavor and Vitamin C retention in the liquid i.e., fruit juice contained therein over the normal shelf life of the product.

This application is a division of application Ser. No. 034,641 filedApr. 6, 1987 issued to U.S. Pat. No. 4,777,088 which is acontinuation-in-part of application Ser. No. 848,940 filed Apr. 7, 1986and now abandoned.

This invention relates to barrier laminates for the containment ofessential oils, flavors, oxygen and vitamin C and to cartons madetherefrom. More particularly, this invention relates to barrierlaminates useful in the manufacture of cartons which hold liquidscontaining essential oils, flavorings and vitamin C such as fruitjuices.

For many years, food experts have been critical of the standardpolyethylene coated paperboard containers currently on the marketbecause not only the essential oils and flavoring contained in fruitjuices could diffuse through the polyethylene coating itself to depositin the paperboard thereby downgrading the initial flavor of the fruitjuice in a very marked manner during its standard shelf life, but alsothe beneficial vitamin C contained in the juice was not retainedtherein.

While the migration of the essential oils and flavorings and the loss ofthe vitamin C could be substantially reduced by the use of a laminatecontaining a metal foil therein mounted as a liner along the interior ofthe container, the economics involved in using a metal foil precludethis solution from being a viable alternative. Despite the fact thatmany attempts have heretofore been made to enable the replacement ofmetallic foil with a polymeric laminate which would enable essentialoil, flavor, and vitamin C retention throughout the standard shelf lifeat a relatively low cost, all such efforts to date have substantiallyfailed to come up with a reasonable substitute for metal foil.

In applicant's recently issued U.S. Pat. No. 4,513,036 a laminate isdisclosed which provides a substantial barrier to the migration ofessential oils and/or flavors therethrough. This is achieved by alaminate comprising, from the outer surface to the inner surfacecontacting said essential oils and/or flavors: a paperboard substrate, aweb of propylene polymer coated thereon and a web of olefin polymeroverlying said propylene polymer web and rendering the resultinglaminate heat-sealable. It has been found that cartons constructed ofthe laminate of U.S. Pat. No. 4,513,036 enable significant flavorretention of the fruit juice contained therein resulting in asignificant extension of the shelf life of the cartons and permit thereplacement of an otherwise required aluminum foil barrier atconsiderable economic savings. However, cartons constructed from theselaminates were no more effective than the conventional "wet strength" orpolyethylene coated board cartons for retaining vitamin C. The foilcartons were clearly more effective but at a cost discouraging theiruse.

Now, in accordance with the present invention, it has been found that alaminate providing not only a substantial barrier to the migration ofessential oils and/or flavors therethrough but providing for retentionof vitamin C is achieved by a laminate comprising from the outer surfaceto the inner surface in contact with the fruit juice: a paperboardsubstrate, a web of nylon coated directly thereon, a web of Surlyndirectly overlying the nylon web and a web of olefin polymer, typicallypolyethylene directly overlying and in contact with the Surlyn web andrendering the resulting laminate heat sealable. It has been found thatcartons constructed of the laminate of the present invention enablesignificant essential oil, flavor and vitamin C retention in the fruitjuice contained therein resulting in a significant extension of theshelf life of the packaged product and permitting the replacement of theotherwise required aluminum foil barrier at considerable economicsavings.

The laminate of the invention further provides an effective barrier tothe passage of oxygen, thus preserving and protecting vitamins and inparticular vitamin C and other nutrients contained in the beverage orjuice product from oxidative degradation. As above noted, this laminateadditionally provides an excellent barrier to the migration of essentialoils and/or flavors therethrough.

In the container field, it has been common practice to use many forms ofmaterials which are heat-sealed or glued and otherwise converted onconventional equipment to form a container or carton. Such containersare those typically known in the trade as "folding boxes", containers orcartons.

By way of example, one such carton is the gable-top milk carton andcarton blanks therefor which are specifically disclosed in U.S. Pat. No.3,120,333 as liquid tight containers. Essentially, blanks used in themanufacture of such containers include a paperboard base, extrusioncoated on both sides with a resin, such as polyethylene, to provide amoisture barrier and to provide means for heat-sealing the carton.

In a typical carton converting operation, once the resin-blanks are cutand scored, the resin on an outer surface of a glue flap and the resinon an inner surface of a carton panel are heated by direct flameapplication while the heated carton surfaces extend in guided butessentially unsupported, i.e., not compressed between two heating jaws,condition over the edges of a conveying belt. The carton panels are thenfolded over to form a flattened tube, the now molten tacky resin on theheated surfaces are pressed together at a downstream nip to form aliquid-tight side seam. The cartons, in a flattened tube form, are thenshipped to users such as dairies or juice manufacturers where they areerected by further heat-sealing, filled and finally sealed.

These familiar gable-top cartons have been extensively used throughoutthe United States to contain milk or juices. While the cartons preparedon the basis of the laminate structures disclosed in U.S. Pat. No.4,513,036 are effective to provide significant flavor and essential oilretention, the problem of the loss of vitamin C still remains.

Many attempts have heretofore been made to overcome the problems of theloss of vitamin C. One attempt involves the use of a liner for theinternal surface of the container comprising a laminate having two ormore laminae of polyolefin or other polymeric material sandwiching ametallic foil therebetween. The presence of the metallic foilsignificantly reduces not only moisture transmission and loss ofessential oils to the paperboard, but also is effective to reduce theloss of vitamin C. The use of metallic foil, however, complicatesprocessing and significantly increases the cost of the resultingproduct.

Other attempts at overcoming these problems have resulted in thesuggestion to use homogeneous, all-plastic containers such as can beformed by a blow-molding operation. By virtue of the fact that thesecontainers are completely formed and that their transportation to thedairy or juice packer thus includes transporting the air in them,shipping charges are substantially increased over shipping charges forsimilar volume containers which can be shipped in a flattened condition.Moreover, such containers are not readily adaptable to inexpensiveprinted decorations. Most important, the conventional plastics used inblow molding have not demonstrated any improvement in the vitamin Cretention as would justify their use.

All-plastic carton blanks cut and scored in patterns similar to those ofthe resin-coated paperboard cartons described hereinabove have also beendeveloped. However, when these plastic containers are run through atypical resin-coated paperboard converter, extra attention and care hasto be taken with the side-seaming by direct flame application to theunconfined container surfaces.

Thus, while homogeneous all-plastic blanks could possibly be sealed bysome known heat-sealing technique such as a static system wherein theheated areas are supported or confined, for example, between heatingjaws, no such other known techniques are capable of high commercialproduction speed (see U.S. Pat. No. 4,224,092). Moreover, the use ofother sealing techniques would require the converter to purchaseadditional equipment to provide efficient sealing of the all-plasticcontainer at considerable expense and also rendering the currentlyavailable equipment obsolete. Accordingly, such all-plastic containershave not been commercially accepted to any significant degree. In anyevent, the all plastic containers as in the case of the blow moldedcontainers, do not prevent the loss of vitamin C of the juice productcontained therein.

Thus, until the advent of the present invention, no suitable containersfor the containment of fruit juices without loss of vitamin C have beendeveloped which retain the advantages of using paperboard as the basematerial and yet eliminate both the processing and economicdisadvantages of the use of metal foil.

The advantages of the present invention will become more readilyapparent from the following detailed description and drawing in which:

FIG. 1 is a cross-sectional elevation of one embodiment of the laminateof the present invention; and

FIG. 2 is a cross-sectional elevation of an alternate embodiment of thelaminate of the present invention.

FIG. 3 is a graphic representation showing retention of D-limonene ofcartons made from different laminates over differing periods of juicestorage.

FIG. 4 is a graphic representation showing retention of ascorbic acid ofcartons made from different laminates over different periods of juicestorage.

The invention described herein is particularly useful as a paperboardlaminate employed in the manufacture, for example, of containers of manyvarious types. Such containers, for example, may comprise folding boxes,square or rectangular containers or cartons, or simply cylindrical tubeshaving a bottom closure means and generally also a top closure means.

For example only, one particular form of container configuration withwhich the present invention is highly useful is the gable-top carton forthe containment of liquids described, for example, in U.S. Pat. No.3,120,333.

Referring now to FIG. 1, the laminate of the present invention is shownas comprising a paperboard substrate 10 which is most suitablyhigh-grade paperboard stock, for example 0.010 to 0.028" milk cartonstock onto which is applied a web of nylon 12 in a coating weight rangeof 5-15 pounds per ream. Directly overlying said nylon web 12 is a webof Surlyn 13 applied in a coating weight range of 2-6 pounds per ream.Surlyn is DuPont's tradename for the ionomerpoly(ethylene-co-methacrylic acid). Surlyn, its chemical structure,properties, preparation and manufacture as described in detail in theKirk Othmer Encyclopedia of Chemical Technology, 3rd Edition,1984--Supplement Volume. Overlying and in contact with the Surlyn web isa web of heat sealable olefin polymer 14, for example low densitypolyethylene, in a coating weight ranging from about 4 to about 12pounds per ream.

Preferably, the olefin polymer is polyethylene and most preferably, alow density polyethylene. Typical of the preferred low densitypolyethylenes which can be employed as web 14 is Gulf 4517 polyethyleneavailable from Gulf Oil Chemicals Company, Houston, Tex. The olefinpolymer web 14 is applied in a coating weight ranging from about 5 toabout 20 pounds per ream.

A preferred Surlyn is DuPont's Surlyn AD 8255 which is an extrudableterionomer resin (zinc metal salt of an ethylene-based terpolymer) andavailable in pellet form for use in conventional extrusion equipmentdesigned to process polyethylene resins. Surlyn AD 8255 is characterizedby its improved adhesion properties and particularly to nylon.

On the external surface of the paperboard substrate is coated a web ofheat sealable olefin polymer 11, typically polyethylene and mostpreferably low density polyethylene. This external coating of olefinpolymer imparts heat sealability to the ultimate container and alsoimparts a gloss to the external surface of the paperboard which withsuitable but conventional treatment can be directly printed on.

Referring now to FIG. 2, wherein like numerals with a prime (')designation, designate laminae of the same type described in FIG. 1, analternate embodiment of a laminate of the present invention is shown. Inthis alternate embodiment, the paperboard substrate 10' is coated on theexternal surface thereof with a web of heat-sealable olefin polymer 11,typically polyethylene and most preferably, low density polyethylene. Asnoted above, this external coating of olefin polymer impartsheat-sealability to the ultimate container construction and also impartsa gloss to the external surface of the paperboard which can be utilizingconventional techniques directly printed upon. Onto the internal surfaceof the paperboard substrate 10 there is applied a web of Surlyn 13' asdescribed hereinafter. Overlying the Surlyn 13' web and in contacttherewith is a web 12' of nylon over which a web 15' of Surlyn has beendirectly applied. Overlying the web 15' of Surlyn and in contacttherewith is a web 14' of heat sealable olefin polymer which willultimately form the internal surface of the container constructedtherefrom.

The laminates of the present invention can be easily fabricated. Forexample, the nylon and Surlyn or the nylon, Surlyn and olefin polymerwebs can be directly coextruded onto the paperboard substrate.Alternatively, in order to facilitate adhesion between the nylon and thepaperboard, a layer of Surlyn can be simultaneously coextruded betweenthe paperboard and the nylon webs as they are directly coextruded ontothe paperboard substrate. Still further, if desired, a three- orfour-pass coating operation can be employed whereby the nylon polymerweb is extruded onto the paperboard substrate and, or subsequentlyovercoating the nylon barrier web with a web of Surlyn and of olefinpolymer.

Although these specific coating techniques have been described, it isapparent to those skilled in the art that any conventional technique forapplying the nylon, Surlyn polymer and olefin polymer webs to apaperboard substrate can be suitably employed.

The unique barrier effect provided by the laminate of the presentinvention to the transmission of essential oils, flavorings and vitaminC is clearly demonstrated by the following comparative example.

Standard paperboard 1/2 gallon orange juice containers were prepared andfilled with orange juice. The principle essential oil in orange juice isd-limonene. The filled cartons were stored for a period of six weeksafter which time the orange juice was analyzed to determine thepercentage loss by weight of the essential oil d-limonene and thepercentage loss by weight of vitamin C.

The standard 1/2 gallon orange juice container was constructed from alaminate consisting (from the outside of the container in) of 9.0 poundsper ream polyethylene, 0.024 milk carton stock and 20 pounds per reampolyethylene.

Another standard paperboard 1/2 gallon orange juice container wasmodified to contain an aluminum foil lining. The structure from theoutside of the container in was 9.0 pounds per ream low densitypolyethylene, 0.024 milk carton stock, 10 pounds per ream low densitypolyethylene, 0.00035" aluminum foil and 20 pounds per ream low-densitypolyethylene.

A third class of comparative standard paperboard 1/2 gallon orange juicecontainer was prepared from the laminate of U.S. Pat. No. 4,513,036comprising from the outside of the container in 9.0 pounds per reampolyethylene, 0.024 milk carton stock, 10 pounds per ream of extrusioncoating grade polypropylene and 10 pounds per ream low densitypolyethylene as well as with other coating weights of polypropylene andpolyethylene.

Finally, standard paperboard 1/2 gallon orange juice containers wereprepared using nylon, Surlyn, polyethylene coextrusion with severaldifferent coating weights of nylon.

The details and results of the experiments follow:

Retention of the essential oil, d-limonene, and of vitamin C, ascorbicacid, are the primary criteria for extended shelf life cartons fororange juice. A six week shelf life study, monitoring the effect ofusing various barrier layers, including barrier layers in accordancewith the invention, in the carton construction, on the retention ofthese components, was carried out. The methodology and results of thisstudy follow:

EXPERIMENTS

Two sets of experimental cartons were evaluated and compared to thestandard wet strength, polypropylene and foil lined cartons ford-limonene and ascorbic acid retention over a six week period. Theexperimental cartons were prepared using board coatings which consistedof:

(1) nylon/surlyn/polyethylene coextrusion, with 5, 10 and 15 lbs/rmcoatings of nylon, and

(2) polypropylene/ethylene methyl acrylate/polyethylene coextrusion withseveral different coating weights of polypropylene and polyethylene.

Actual thicknesses of experimental barrier layers were determined bymicroscopy. The MoCon unit, Ox-Tran 10/50, was used to make the oxygentransmission rate measurements. The extrusion coated boards wereconverted into cartons and then filled with orange juice from a singlebatch at one facility. The standard wet strength, polypropylene, andfoil lined cartons were filled at the same time. Filled cartons werekept in refrigerated storage at 37° F. for the duration of the test.Orange juice samples were taken the next day after filling for the zeroweek reading, and at weekly intervals thereafter. Samples were testedfor d-limonene and ascorbic acid by the procedures as hereinafter setout. In every case, except for the foil lined cartons, samples from twocartons were analyzed every week.

The method for determining d-limonene involves a co-distillation oforange juice with isopropyl alcohol, followed by acidification of thedistillate and titration with standardized KBr-KBrO₃ solution. Thereaction involves release of bromine, in situ, which then reacts withd-limonene's double bond to form limonene tetrabromide.

The ascorbic acid concentration in orange juice was determined by amodified 2,6-dichlorophenol-indophenol titration method. The methodinvolves titrating a sample containing ascorbic acid in the presence ofmetaphosphoric acid and acetic acid with the dichlorophenol-indophenolstandard solution until a distinct pink color persists for 5 seconds.The dichlorophenol-indophenol standard solution is used as a standardoxidizing agent which is colored blue in alkali and red in acid, whilethe reduced form is colorless.

To validate these methods, several sets of orange juices packaged invarious containers were purchased and analyzed for % limonene and %ascorbic acid utilizing the above methods. The results of triplicateanalysis of Tropicana orange juice packaged in various containers areoutlined below for reference:

    ______________________________________                                                                  % Ascorbic Acid                                     Sample ID      % Limonene (mgs per 100 mL)                                    ______________________________________                                        Glass Container                                                                              0.0203     46.4                                                Frozen Concentrate                                                                           0.0174     45.7                                                Conventional PE                                                                              0.0129     29.5                                                Coated Cartons                                                                ______________________________________                                    

RESULTS AND DISCUSSION

The structures and oxygen transmission rates of the various experimentalbarrier layers used in this study are shown in Table I. The measuredthicknesses of the nylon layers were very close to the target values.The oxygen transmission rates shown by these films are in the expectedrange based on other measurements reported in the literature. The cartonconstructions for the standard wet strength, polypropylene, andfoil-lined cartons and the associated oxygen transmission values arenoted in Table II for reference.

The results of the d-limonene and ascorbic acid retention analysis arepresented in Tables III and IV. For ease of interpretation, the resultsfor the nylon based samples, along with the benchmark samples, areplotted in FIGS. 3 and 4. It is clear that the results for the threenylon based cartons are indistinguishable from those for the foil linedcartons for both d-limonene and vitamin C retention. Clearly, a 5 lbs/rmcoating of nylon provides a barrier as good as foil and no furtheradvantage is gained by increasing the coating weights to 10 and 15lbs/rm. The polypropylene carton shows a clear advantage over thestandard wet strength or polyethylene coated carton in d-limoneneretention but no real advantage in vitamin C retention.

The results for polypropylene based cartons are shown in FIGS. 3 and 4.For d-limonene retention, all of the polypropylene based cartons showimproved performance over the standard wet strength or polyethylenecoated carton. However, there appear to be no clear trends inperformance among the various polypropylene based cartons, which rangein polypropylene coating weights from 1.7 to 19.6 lbs/rm. This may implythat the improved performance of polypropylene based cartons isattributable to some synergistic effect of polypropylene andpolyethylene rather than the thickness of the polypropylene layer.

The vitamin C retention results of polypropylene based cartons aresimilar. There is no clear trend with polypropylene coating weight,except when the total polymer coating weight is about twice as high asthe polypropylene carton. And, even then, the effect is small. Theseobservations are not surprising in view of the data on oxygentransmission rates.

The results on ascorbic acid retention, coupled with the oxygentransmission rate data on all of the samples examined indicate that therange of interest in this application for barrier layer oxygentransmission rates is between ˜10 and ˜130 cc/100 sq in/24 hr. At ratesabove ˜130 cc/100 sq in/24 hr, no benefit is obtained; and, at ratesbelow ˜10 cc/100 sq in/24 hr. no further improvement in benefits isavailable. This observation is of value in determining the most costeffective coating weight for nylon and also for evaluation of otherbarrier layers.

SUMMARY OF RESULTS

(1) Inclusion of a nylon layer at a coating weight of 5 lbs/rm. orhigher, in the carton construction provides d-limonene and vitamin Cretention levels indistinguishable from the foil lined carton.

(2) The polypropylene carton is clearly superior to the standard wetstrength polyethylene carton in d-limonene retention; but, as expected,provides no advantage in vitamin C retention.

(3) Varying the polypropylene content in the polypropylene coated cartonconstruction from a high of 19.6 lbs/rm to a low of 1.7 lbs/rm showed nosignificant difference in d-limonene or vitamin C retention.

                  TABLE I                                                         ______________________________________                                        EXTENDED SHELF LIFE STUDY                                                     STRUCTURES AND OXYGEN TRANSMISSION RATES OF                                   BARRIER LAYERS FOR VARIOUS CARTONS                                            Nylon Based:                                                                  Nominal/Measured*                                                             (lbs/3000 sq ft)       O.sub.2 Transmission                                   Sample                                                                              Nylon    Surlyn   Polyethylene                                                                           (cc/100 sq in/24 hr)                         ______________________________________                                        1      5/5.6   4/4.1    6/12.8   9.4                                          2     10/9.9   4/2.9    6/11.2   4.3                                          3     15/14.6  4/3.5    6/12.8   Not tested                                   ______________________________________                                        Polypropylene Barrier Film Optimization:                                      Measured*                                                                     (lbs/3000 sq ft)                                                                              Ethylene                                                            Polypro-  Methyl   Polyethy-                                                                             O.sub.2 Transmission                         Sample                                                                              pylene    Acrylate lene    (cc/100 sq in/24 hr)                         ______________________________________                                        Pl    6.8       4.2      7.5     320                                          P2    6.5       4.5      9.9     331                                          P3    3.4       3.5      7.2     532                                          P4    1.7       3.5      9.2     513                                          P5    19.6      6.0      18.9    130                                          ______________________________________                                         *Densities used in computation:                                               Polyethylene 0.923 gm/cc                                                      Polypropylene 0.905 gm/cc                                                     Nylon 1.13 gm/cc                                                              Surlyn 0.940 gm/cc                                                            Ethylene Methyl Acrylate 0.923 gm/cc                                     

                  TABLE II                                                        ______________________________________                                        EXTENDED SHELF LIFE STUDY                                                     STRUCTURES AND OXYGEN TRANSMISSION RATES                                      OF COMPARISON CARTONS                                                         Carton:                                                                       Nominal Side Wall Construction                                                                         O.sub.2 Transmis-                                    per 3000 sq ft           sion (cc/100 sq                                      Gloss Side    Board   Matte Side in/24 hr)                                    ______________________________________                                        Standard                                                                               9 lbs PE 280 lbs 11 lbs PE                                                                              280                                        Wet                                                                           Strength                                                                      Polypropy-                                                                            10 lbs PE 280 lbs 12 lbs PP/10                                                                           Not Tested                                 lene                      lbs PE                                              Foil lined                                                                            10 lbs PE 280 lbs 10 lbs PE/14.9                                                                         .06                                                                  lbs Al/20 lbs                                                                 PE                                                  ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        EXTENDED SHELF LIFE STUDY                                                     % D-LIMONENE RETENTION                                                                WEEK                                                                  Sample+   0       1      2    3    4    5    6                                ______________________________________                                        Nylon Based:                                                                  1         .0236   .0217  .0204                                                                              .0207                                                                              .0206                                                                              .0208                                                                              .0200                                      .0232   .0218  .0209                                                                              .0207                                                                              .0201                                                                              .0204                                                                              .0201                            2         .0236   .0216  .0209                                                                              .0198                                                                              .0208                                                                              .0207                                                                              .0200                                      .0237   .0214  .0210                                                                              .0204                                                                              .0202                                                                              .0202                                                                              .0204                            3         .0236   .0216  .0207                                                                              .0193                                                                              .0196                                                                              .0202                                                                              .0197                                      .0239   .0210  .0208                                                                              .0194                                                                              .0198                                                                              .0202                                                                              .0194                            ______________________________________                                        Comparisons:                                                                  Wet Strength                                                                            .0231   .0196  .0179                                                                              .0155                                                                              .0147                                                                              .0134                                                                              .0120                                      .0231   .0195  .0174                                                                              .0156                                                                              .0148                                                                              .0136                                                                              .0118                            Polypropylene                                                                           .0240   .0206  .0203                                                                              .0192                                                                              .0184                                                                              .0180                                                                              .0153                                      .0237   .0208  .0198                                                                              .0188                                                                              .0186                                                                              .0174                                                                              .0151                            Foil      NT*     .0218  NT   .0189                                                                              NT   .0201                                                                              NT                               ______________________________________                                        Polypropylene Barrier Film Optimization:                                      P1        .0235   .0214  .0202                                                                              .0188                                                                              .0184                                                                              .0172                                                                              .0162                                      .0235   .0215  .0200                                                                              .0192                                                                              .0184                                                                              .0174                                                                              .0162                            P2        .0234   .0219  .0203                                                                              .0184                                                                              .0182                                                                              .0165                                                                              .0162                                      .0244   .0218  .0200                                                                              .0176                                                                              .0184                                                                              .0170                                                                              .0161                            P3        .0237   .0224  .0199                                                                              .0186                                                                              .0177                                                                              .0165                                                                              .0138                                      .0234   .0231  .0196                                                                              .0184                                                                              .0176                                                                              .0166                                                                              .0138                            P4        .0232   .0213  .0199                                                                              .0172                                                                              .0172                                                                              .0155                                                                              .0144                                      .0237   .0214  .0198                                                                              .0182                                                                              .0172                                                                              .0154                                                                              .0143                            P5        .0227   .0208  .0188                                                                              .0172                                                                              .0171                                                                              .0165                                                                              .0147                                      .0234   .0198  .0188                                                                              .0170                                                                              .0168                                                                              .0164                                                                              .0146                            Grand     02352                                                               Avg:                                                                          ______________________________________                                         *NT = Not Tested                                                              +For Detailed Constructions, see Tables I and II                         

                  TABLE IV                                                        ______________________________________                                        EXTENDED SHELF LIFE STUDY                                                     ASCORBIC ACID RETENTION                                                       (Milligrams Per 100 mls Orange Juice)                                                 WEEK                                                                  Sample+   0       1      2    3    4    5    6                                ______________________________________                                        Nylon Based:                                                                  1         47.4    45.9   44.3 39.3 41.1 34.7 36.5                                       50.1    45.3   44.7 40.6 43.6 34.2 37.0                             2         48.5    45.3   43.3 40.2 41.1 38.1 37.5                                       48.5    45.3   42.9 41.5 41.1 36.7 37.5                             3         48.5    44.8   43.3 39.7 39.6 36.7 40.5                                       50.1    46.4   43.8 40.2 38.6 36.2 39.5                             ______________________________________                                        Comparisons:                                                                  Wet Strength                                                                            47.4    43.2   37.3 32.9 30.2 23.8 22.3                                       49.0    45.3   37.3 33.3 31.2 24.3 21.8                             Polypropylene                                                                           48.0    45.9   41.0 34.2 32.2 24.3 21.8                                       49.5    44.8   41.5 34.2 31.7 24.3 22.8                             Foil      NT*     45.3   NT   40.2 NT   38.1 NT                                         NT      45.3   NT   42.5 NT   37.7 NT                               ______________________________________                                        Polypropylene Barrier Film Optimization:                                      P1        44.8    43.8   39.6 36.1 32.2 20.8 21.8                                       48.5    43.2   38.7 35.2 33.2 21.3 21.3                             P2        47.4    43.2   37.3 34.2 31.7 18.3 17.7                                       47.4    43.2   38.2 34.2 31.2 19.3 16.7                             P3        45.9    44.3   37.3 33.8 28.7 20.8 19.2                                       48.0    43.8   37.3 33.8 31.7 19.8 18.7                             P4        49.0    42.7   37.3 35.2 31.2 18.8 22.3                                       48.0    43.2   38.2 35.6 30.2 18.8 21.3                             P5        49.0    44.8   40.1 35.2 33.2 25.3 26.3                                       49.0    45.3   38.7 35.6 35.7 25.3 27.4                             Grand     48.2                                                                Avg:                                                                          ______________________________________                                         *NT = Not Tested                                                              +For Detailed Constructions, see Tables I and II                         

In accordance with a preferred embodiment of the invention, the laminatehas incorporated into a suitable intermediate layer particles of apigment such as aluminum powder or a food grade dye for providing asuitable and more attractive coated product.

The adhesion characteristics of the film layers are not interfered withand the use of the pigment and/or colorant is applicable to acoextrusion process.

The pigmented or colored coated paperboard material comprises apaperboard substrate 10 onto which are coextruded the nylon 12, followedby the Surlyn 13 and the heat sealable olefin polymer 14, with thepigment or colorant incorporated into either the nylon 12 or Surlyn 13layer and preferably in this construction, into the nylon.

In the structure shown in FIG. 2, the pigment or colorant isincorporated into any of the layers of Surlyn 13' nylon 12' and Surlyn15'.

The pigment or colorant is preferably aluminum particles, but the coatedpaperboard can be pigmented with any color i.e., white, terra-cotta,blue, yellow, so long as the pigment chosen has sufficient heatresistance to withstand the extrusion conditions. Typically, anysuitably colored heat resistant pigment can be employed, i.e., animalpigments, synthetic pigments, elemental pigments e.g., carbon black oraluminum powder, inorganic pigments such as inorganic oxides, sulfides,hydroxides, carbonates, silicates, chromates, sulfates, and the like, aswell as organic pigments. As colorants, any certified color i.e., FD & Ccolor permissible for use in foods, drugs or cosmetics may be used ifthey additionally meet the requirement of compatibility with theextrusion process.

The pigment or colorant is incorporated into the intermediate filmforming layer i.e., nylon or Surlyn in an amount of from about 1/2 toabout 15 weight percent, preferably from 1 to 10 weight percent and morepreferably from 11/2 to 6 weight percent.

The aluminum is preferably used in the form of finely divided aluminumpowder and is most conveniently added to the nylon or Surlyn in the formof a blend thereof in the same polymer.

If TiO₂ is used as a pigment, it can be used, as is conventional in theplastic industry.

The various layers including the intermediate layer containing thepigment are extruded or coextruded onto the paperboard substrate bymethods well known in the art.

In accordance with still another embodiment of the invention, it hasbeen found that satisfactory results with respect to essential oil,flavoring and Vitamin C retention are realized if the nylon is extrudeddirectly onto paperboard and the nylon surface then primed. Followingpriming, polyethylene is extruded directly onto the nylon surface.

In accordance with this embodiment of the invention, a laminateconstituting an effective barrier to the migration of essential oilsand/or flavorings therethrough and for the retention of the vitamin Ccontained in the juice, is provided comprising from the outer surface tothe inner surface which is in contact with the liquid, a paperboardsubstrate, a web of nylon which has been primed prior to the applicationof an overlying web of olefin polymer and preferably polyethylene. Thislaminate is suitable for use in constructing the standard juicecontainer as hereinbefore described.

The nylon is applied in an amount of 5 to 17 pounds per ream, the nylonsurface treated with corona and then gas flame priming.

Subsequently 12.0 pounds per ream of polyethylene #4517 are applied ontothe nylon.

What is claimed is:
 1. A container for liquids containing essential oilsand/or flavorings and vitamin C constructed from a laminate providing aneffective barrier to the migration of essential oils and/or flavoringstherethrough and for retention of vitamin C contained in fruit juicescomprising, from the outer surface to the inner surface contacting saidfruit juice; a paperboard substrate, a web of nylon coated directlythereon, a web of poly(ethylene-co-methacrylic acid) partiallyneutralized with sodium and zinc cations directly overlying and incontact with said nylon web and a web of olefin polymer directlyoverlying and in contact with said web of poly(ethylene-co-methacrylicacid).
 2. A container for liquids containing essential oils and/orflavorings and vitamin C according to claim 1, wherein said laminateadditionally comprises an outer olefin polymer web on the surface of thepaperboard substrate opposite the nylon web coated surface.
 3. Acontainer for liquids containing essential oils and/or flavorings andvitamin C according to claim 1, wherein said laminate additionallycomprises a web of poly(ethylene-co-methacrylic acid) partiallyneutralized with sodium and zinc cations between the paperboardsubstrate and the nylon web normally adjacent thereto.
 4. A containerfor liquids containing essential oils and/or flavorings and vitamin Caccording to claim 1, wherein in said laminate one of said nylon andpoly(ethylene-co-methacrylic acid) webs contains a pigment or food gradecolorant.